Automatic telephone-exchange system.



C. L. GOODRUME AUTOMATIC TELEPHONE EXCHANGE SYSTEM.

APPLICATION men SEPT. 1, I915.

Patenwdi 10%.) 4, 1917 CHARLES Ii. GOODRUIVI, OF NEW YORK, N. Y., ,ASSIGNOR, BY MESNE ASSIGNMENTS, T0 WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

AUTOMATIC TELEPHONE-EXCHANGE SYSTEM.

Application filed. September 7, 1915.

To all whom it may concern."

Be it known that I, CHARLES L. GooDRUM, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Automatic Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

In automatic telephone systems employing line finders, it is usual to provide enough line finders to take care of the-traflic under ordinary conditions, and it has been found that ordinarily ten line finders are suflicient to take care of the trafiic on one hundred lines. These hundred lines are usually divided into ten groups of ten lines each, one line finder being allotted to each group. Each line finder normally handles the trafiic originating in its group of lines, but should it be busy on a call, the next call originating in the group is passed along, to the next line finder, and so on, until it arrives at an idle line finder. In a step-by-step panel type line finder switch, the movable element has two movements: a rotary one and a longitudinal one. These switches are so arranged that the rotary movement may be dispensed with when the call originates in the group of lines to which the switch is individual, and when the call originates in any other group of lines a rotary movement of from one to nine steps is necessary before the movable element is in position to begin its longitudinal movement in search of the line desired. This condition it is desired to avoid whenever possible because of the resultant slowing down of traffic.

While ordinarily enough line finders are provided totake care of the normal traflic, it sometimes happens that an abnormal amount of trafiic originates in one or more of the groups of lines, and it has been found desirable to be able to increase, at will, the number of line finders allotted to any group of lines. To be able to do so insures that the "slowing down of traflic, due to the causes above enumerated, is avoided. Also it is desirable, should for any reason the allotted line finder become inoperative, to be able to substitute therefor another line finder that acts as, and really is, a duplicate of the original. i

The object of this invention is, therefore, the provision of means for inserting, in an Specification of Letters Patent.

Patented Dec. at, 161'? Serial No. 49,288.

automatic telephone exchange system, an overflow finder which acts as a substitute for or duplicate of the finder with which it may be associated.

The drawing attached to this specification illustrates this invention applied to a stepby-step panel type system, with so much of the system illustrated as is necessary for an understanding of the invention. For a detailed description of a telephone system to which this invention is designed to be applied, reference may be. had to applicants copending application, entitled Automatic telephone exchange systems, Serial No. 872,743, filed November 18, 1914.

The drawing shows three groups of lines,

A, B and C, each group having associated therewith a group relay unit controlling the circuit leading to the line finder switch individual to the group of lines, and also to the other line finder switches of the ex change. Associated with the third contact of each line finder side switch is a jack 27, through which the starter wire 26 extends to the next line finder switch. A11 auxiliary line finder switch 29 has a plug 30 attached thereto, which may be inserted in the jack 27, thus associating said auxiliary switch with the switch attached to the jack 27, the auxiliary switch acting as a duplicate of the one with which it is associated, in that it takes care of calls originating in the group of lines, to which the original switch is individual, without the'necessity of the movable element of the switch taking a preliminary rotary step. Also it allows the succeeding regular switches to act as overflow switches in case the traffic originating in the lines of the group becomes too great to be taken care of by the regular and auxiliary switch.

When the subscriber at substation 10 removes his receiver from the switchhook, a circuit is closed for the line relay 11, said circuit leading over the line conductors 12 and 13 and through the telephone set of substation 10. This relay 11 thereupon closes a circuit for relay 14 to start a finder searching for this calling line, this circuit leading from battery through the left winding of relay 11, left armature and back C011. tact of the cutoff relay '15, conductor 16, contacts 17, 18, conductor 19, left armature andback contact of relay 20,c0nd110t0r 31,- group relay 14 to ground; Relay 14 there- 7 upon locks itself up in series with the line Ill for the calling line, assuming that the line .finder normally associated with the starter wire'22 is not in use. The relay 23 was energized upon the energlzation of relay 14,

and .is made slow-acting for a. purpose to be setforth later. The side switch 21 moving into position 2 closes a circuit for a magnet (not showni, which raises the brush rod, during which'movement the set of brushes wipes over the. group containing the calling line, this circuit including the right armature and front contact of relay 23, conductor "24 and the right armature and front contact of relay 14. 'When the brushes arrive upon the terminals representing the line of the subscriber initiating the call, the cutoff relay 15 of snch line is energized over a circuit in a manner well understood. Cutoff relay 15 at its left armature opens the circuit of relay 14, resulting in the finder being brought to rest upon the calling line terminals. When the cutoff relay 15 operates and denergizes the relay 14, theside switch moves to position 3.

magnet of the finder normally. associated 'with the third group of vlines.

Associated with the relays 14 and 23 of each group of lines is a relay .20, which whentenergized opens at its right armature and loackfcontact the circuit of the release magnet of the associated finder. When the side switch of the finder of the line-group A moves to position 3, arm 25 thereof extends the conductor 26 through the jack 27 to conductor 42, which leads through back contacts of the relay '23 of the next line group to the driving magnetof the line finder normally associated with said group, orif such finder is busy, the arm 25 and thirdcontact of its side switch 21 further extends the conductor26 tothenext finder and so on until an idle finder is found.

Assuming now that a second call is initiated in the first line group and that the finders normallyassociated with the, first two line groups are busy. Under such conditions the arms '25 of their side switches will-be in their third positions, extending the :conductor 26 through to the. driving The line relay 32 upon its energ1Zat1on,.--due..torthe aclosure of theline circuit uponthe initiation. of-a call at the; substation connectedto .conductors 34, closes a-circuit;for-.the

group relay 14 to start thepreselected finder.

This finder; is the thirdconeofrom the :left

shown in the figure. The circuit is as follows: battery, left winding of relay 32, conductor 35, left armature and back contact of cutoff relay 36, conductor 37, contacts 38, 39 of relay 32, conductor 40, left armature and back contact of relay 20, conductor 31, group relay 14 to ground. Relay 14 energiZes and closes the circuit of slow-acting relay 23, which at its right armature and front contact closes the driving circuit to the preselected linefinder as follows ground, right armature and front-contact of relay 14, conductor 24, right armature and front contact of relay 23, conductor 26, arm 25 .and third contact of the side switch. jack 27, conductor 42, left armature and back contact of relay 23 of the next line group, and so on to the arm 25 and first contact of the slde switch of the third or idle line finder,

to the conductor 23 which leads to battery through the rotary driving magnet of said line finder (not shown).

The drlving magnetof the third finder referred to, rotates its brush rod, until it is in a position corresponding to this line group. lVhen this position is reached, a. ground is found at the right armature and front contact of relay 14 by way of conductors 24 and 22, completing the circuit for the escapement magnet of this finder,

cutting the rotary driving magnet out of circuit and cutting in the vertical magnet of such finder.

When the relay 23 closed at its right armature and front contact the circuit just traced to the rotating drivingmagnet of the said finder, it closed at its left armature and front contact a circuit for the relays 20. One of these relays is associated with each of the line finders, and by opening the release circuits of the associated finders at theirright armatures, and back contact-s, prevents them from restoring their side switches and thus breaking the starting circuit just traced. It will be noted that these relays remain energized as long as relay 23 is excited, and since this relay is de'energized only by the deenergization of relay 14, which in turn is deenergized by the operation of the cutoff relay of the calling line, it will be apparent that therelease circuits for the finders, through whose side switches the starting circuit passes, cannot be closed until the finder which has been set in motion has reached the calling line. These relays are then immediately released by the deenergization of relay 14 and consequent de'e'nergization of relay If the traflic in any group of lines, as group A, is abnormally large, and the trafand possibly to an objectionable degree.

Toitake care of this'condition, a jack 27 for.- each rline group. is arranged as shown,

interposed between the third terminal of the side switch 21 and the left armature and back contact of the slow acting relay 23 associated with the next succeeding line finder, so that under ordinary circumstances, when a call is initiated in any group, the starter wire 26 is extended through the third contact of the side switch and the jack 27 to the next succeedingline finder. One ormore auxiliary line finders 29 may be provided, each equipped with a lug 80, for insertion into any of the jacks 2 by which means the auxiliary line finder may be attached to and act as a duplicate of the line finder with which it may be associated.

What is claimed is:

1. In a telephone system, telephone lines divided into groups, a series of line finder switches common to said lines each of said switches being normally allotted to a group of lines, an auxiliary line finder switch, and means for temporarily inserting in and removing said auxiliary switch from between any two of the switches of said series.

2. In a telephone system, telephone lines divided into groups, a series of line finder switches common to said lines each of said switches being normally allotted to a group of lines, an auxiliary line finder switch, and

a switch for temporarily inserting in and removing said auxiliary switch from said series so as to allot one or two switches for the use of any desired group of lines.

3. In a telephone system, telephone lines divided into groups, a series of line finder switches common to said lines each of said switches being normally allotted to a group of lines, an auxiliary line finder switch, and a contact device for temporarily inserting in and removing said auxiliary switch from between any two of the switches of said series.

4. In a telephone system, telephone lines,

divided into groups, a series of line finder switches one for each group of lines and normally allotted thereto, a starter circuit common to said series of line finders and arranged to be extended when a switch is operating from said operating switch to the next idle succeeding switch of said series, an auxiliary line finder switch, and a plug and jack for temporarily inserting in and removing said auxiliary switch from said starter circuit between any two of the switches of said series.

In witness whereof, I hereunto subscribe my nalne this 2nd day of September, A. l).

CHARLES L. GOODRUM.

Gopiee of this patent may he obtained for five cents each, by addressing the "Gommtssioner of Patents, Washington, D. (2. 

